1. Field of the Invention
The present invention relates to an image pickup apparatus, and more specifically relates to an image pickup apparatus capable of generating, from multiple images with differing exposure amounts, a synthesized image with a wide dynamic range.
2. Description of the Related Art
Various types of apparatuses are known as image pickup apparatuses for electronically taking images of subjects, such as TV cameras, video cameras, electronic cameras, and so forth.
Common image pickup devices such as CCDs or the like used in such image pickup apparatuses have properties in which the dynamic range thereof regarding gradations is narrower than that of silver-salt film used with conventional silver-salt cameras, and accordingly, in the event that an image is taken of subject with great differences in light and dark parts, e.g., in the event that an image is taken in bright sunlight both into the sun and at shadows at the same time, taking the image so that the exposure for one is suitable may result in the other blacking out or whiting out (white scattering).
An image pickup apparatus which synthesizes multiple images with differing exposure amounts and generates one wide dynamic range image so that both the light parts and dark parts are suitably reproduced even with image pickup scenes with a great difference in light and dark parts, performing so-called SL (Super Latitude) processing, has been conventionally proposed.
For example, Japanese Unexamined Patent Application Publication No. 2000-92378 proposes, as such, an image pickup apparatus comprising: image pickup means capable of taking images of the same subject with differing exposure amounts and generating image signals for multiple screens having differing exposure amounts; and means for synthesizing the image signals for multiple screens having differing exposure amounts obtained by the image pickup means and generating a wide-dynamic-range synthesized image; further comprising at least two control means of a normal photography control means according to a normal photography mode for generating one screen of image pickup signals from the image pickup means, forced wide-dynamic-range photography control means according to a forced wide-dynamic-range photography mode for forcibly generating a wide-dynamic-range synthesized image, and automatic wide-dynamic-range photography control means according to an automatic wide-dynamic-range photography mode for automatically and selectively generating a wide-dynamic-range synthesized image based on subject information or photography setting information; and mode setting means for selectively setting one photography mode from the photography modes corresponding to these control means.
Further, the Publication describes further comprising, in addition to the above configuration, suitability judging means for performing judgment regarding whether or not the information obtained as generating processing conditions for generating a wide dynamic range synthesized image is information which matches the generating processing for a wide dynamic range synthesized image, and means for, in the event that the photography mode set by the mode setting means and the judgment results made by the suitability judging means do not match, instructing changing the information parameter settings or photography settings, or instructing a re-take.
Thus, the image pickup apparatus according to the Publication judges the suitability of SL processing from multiple images taken with differing exposures, and in the event that there is no suitability, SL processing is not performed.
Now, the SL processing is a type of image processing, and is not restricted to execution with image pickup apparatuses alone, but can also be performed with other processing devices, such as personal computers for example, or the like.
There are cases wherein, even in the event that sufficient SL processing is difficult to perform due to the computation power, memory capacity, etc., of the image pickup apparatus itself, high-quality SL processing can be performed by using an external processing device or the like having relatively high computational processing capabilities and sufficient memory and the like, as described above.
However, with a conventional example as described above, in the event that the SL processing is cancelled, only a standard exposure image is output, and there is no consideration given to processing with external devices, so such later processing could not be handled.
Also, automatically judging whether or not performing SL processing is suitable is actually difficult to realize, so there are cases wherein, even in the event that judgment is made that SL processing is suitable, the results are unacceptable when viewed by humans. However, with the conventional example, SL processing is performed even in such cases based on the automatic judging results, so images which are subjectively perceived to be deteriorated are forcibly recorded to a recording medium or the like.
Further, with the conventional example, in the event that judgment is made that performing SL processing is not suitable, the user had no way of knowing how to attain a suitable state, so operability was not good by any means.